缺電子基取代之8，8-bis（methoxycarbonyl）heptafulvene（2）和給電子基不對稱取代之6-methyl-6-phenylfulvene（5）進行還化加成反應研究探討。由實驗結果顯示，溫度效應為控制其還化加成反應之重要因素．Heptafulvene2只會和fulvene5進行[8+2]還化加成反應，且意外地只得到[8+2]"順式"加成生成物6和7。在所有進行的反應當中，並未有分離出任何的[4+2],[6+4]與（anti）[8+6]還化加成生成物。其進行還化加成反應只顯示出的“反向”位向選擇性（regioselec-tivity），可以歸因於heptafulvene2和fulvene5的環外取代基（exosubstituents）相互之間巨大排斥力所至。
Thermal cycloaddition reaction of electron-deficient 8,8-bis (methoxycarbonyl) heptafulvene (2) with electron-rich unsymmetrically 6,6-disubstituted6-methyl-6-phenylfulvene (5) was examined to determine the effects ofthe fulvene exocyclic substituents on this cycloaddition. 2 eacted with 5 to afford only the unexpected [8+2] adducts6 and 7,both with the methylgroup cis to H-6. In no caseswere [4+2], [6+4]and [8+6]cycloadducts obtained. The reaction shows a temperature dependency. The exclusively anti regioselectivity can be attributed tothe enormoussteric repulsion between the exocyclic substituents on theheptafulvene andfulvene.
